Thesis
An investigation into the evolution of the neo-Y chromosome in Oncorhynchus nerka
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/101433
Abstract
Sockeye salmon (Oncorhynchus nerka) have a unique set of sex-chromosomes among the Pacific salmon and trout. Males have one large metacentric Y chromosome homologous to two smaller acrocentric X chromosomes (X1X2Y) while females have four acrocentric X chromosomes (X1X1X2X2). In this study, we determined that the sockeye neo-Y chromosome consists of a fusion between rainbow trout chromosome arms OMY8q and OMY2q. OMY8q is a shared ancestral sex chromosome with coho salmon (Oncorhynchus kisutch) and OMY2q is autosomal in all other species in the genus. Evolutionary theory predicts that neo-sex chromosomes arise when sexually antagonistic genes reside on autosomes and translocate to ancestral sex chromosomes, thereby resolving sexual conflict and increasing fitness of the population. We tested this hypothesis using a novel comparative genome scan approach with sockeye and coho salmon, and we found one microsatellite marker on OMY2q (OMM1603) that showed strong signatures of sexually antagonistic selection in both species. These findings validate a long standing hypothesis regarding sex-chromosome evolution, for which there was previously little empirical evidence.
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Details
- Title
- An investigation into the evolution of the neo-Y chromosome in Oncorhynchus nerka
- Creators
- Joshua Faber-Hammond
- Contributors
- Ruth B. Phillips (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525092301842
- Language
- English
- Resource Type
- Thesis